1. Field of the Invention
The present invention relates to the handling of articles, such as beverage containers moving at high speed in modern production facilities. Of special interest is the use of the invention in the food and beverage industry and in particular the handling of bottles and cans containing alcoholic and non-alcoholic beverages. Examples of such beverages include beer and beer-based drinks such as shandies; coolers and low or non-alcoholic beers; non-alcoholic soft drinks such as colas; water; fruit juices and the like.
2. Description of Prior Art
In many industries and, in particular, the beverage industry, product units such as bottles and cans are often transported in production facilities in lines or streams at high speed using conveyor systems. In some instances, the pathway defined by the conveyor is not much wider than the moving container but is sufficient to allow for free movement of the container along the conveyor. The conveyor is set up such that the containers generally travel along it adjacent to one sidewall or rail of the conveyor. This generally occurs even if the width of the conveyor is greater than the width of the container. For example, empty beer bottles, (very common articles to which the present invention relates) are generally required to be transported from a rinsing station to an automated filling device and, subsequently, to a bottle labeling device, often at rates of up to 1500 or more bottles per minute. Obviously, in an operation involving so many bottles processed at those rates, there are going to be a number of bottles which are commercially unacceptable for various reasons. For example, a bottle may be under-filled, or over-filled, with beer or the bottle label may be mis-aligned or even totally missing. Such bottles are not acceptable and must be separated from the acceptable bottles prior to the latter proceeding to a packaging station. There are many known systems for inspecting the stream of bottles and detecting any such unacceptable or defective bottles. (refer for example to U.S. Pat. Nos. 5,979,635 and 6,043,504) Once any unacceptable bottle has been detected it must be removed from the line or stream. It will be appreciated that commercial reality means that the production line cannot be stopped or generally even slowed down each time an unacceptable bottle has to be removed. It is also important to note that adjacent bottles in the moving line might be, and often are, in contact. This clearly complicates the removal of each unacceptable bottle since it must be removed without affecting the speed or direction of movement of the two adjacent and acceptable bottles and the effect the latter bottles may have on bottles adjacent to them and so on. Moreover, although in some instances, simple rejection to a rejection bin of unaccepted bottles is all that is required, there are instances when it is desirable to direct rejected bottles to one of several possible locations and in a controllable manner; in essence, sort the bottles. For example, a bottle, which has been found to have lower than the prescribed amount of beer, (i.e. it is a xe2x80x9clow-fillxe2x80x9d) might be re-directed to a station which empties the bottle of beer and the beer and the bottle are reclaimed. In another case a bottle with the label missing could result in the rejected bottle being returned to the labeller. In contrast, an unacceptable can is not usually reused (apart from being recycled for metal content) and hence, such sorting of rejected cans would probably not occur.
Many commonly used rejection or sorting systems involve an actuator assembly which includes a piston carrying a bottle-contacting member or pad which assembly is located adjacent the side of the conveyor, the actuator member being arranged to extend across the conveyor at right angles to the direction of travel of the bottles and to be retracted along the same path. As it advances, the pad contacts the body of the moving bottle to be diverted with more or less force depending on a number of factors. The bottles are essentially struck out of the moving line of bottles hopefully leaving the adjacent, and especially the immediately following, bottle unaffected as regards their velocity and direction. The diverted bottles may be directed off the conveyor to a collection receptacle or redirected on to another conveyor adjacent the first conveyor; refer, for example, to U.S. Pat. No. 3,133,640. A number of disadvantages are associated with this type of device. The use of a fluid, air in the case of a pneumatic activator, can be inconvenient and even cause problems not the least being the constant need to make adjustments to it for various reasons. For example, fluctuations and especially reduction in, or loss of, pressure can result if the device has to operate virtually continuously for an extended period and the air pressure becomes inadequate to sustain the desired piston rejecter stroke. In this situation, additional equipment such as an accumulator tank may be necessary. Such extended use situations can happen if the bottle filler is incorrectly adjusted and a large number of low-fills are produced. Another significant problem is that the pad is relatively narrow and, to be effective, must contact the moving bottle at virtually the longitudinal axis of the bottle to effect a clean redirect. It will be appreciated that with all the variables in this system fine tuning even to maintain a centre of bottle hit is a constant issue. Consequently, as can happen, the actuator is unavoidably triggered early or late, then the pad contacts the bottle off-centre possibly at the leading or trailing edge of the bottle and can cause same to spin or otherwise become unstable which, in combination with the xe2x80x9cpullxe2x80x9d from the conveyor, can result in toppling, hitting an adjacent bottle; etc. Also, the actuator is extended and withdrawn at right angles to the direction of travel of the bottles and both actions must occur prior to the bottle following the rejected bottle arriving at the actuator. If the actuator cycle is not fully completed in time, the next bottle will strike a part of the actuator assembly blocking the conveyor and this would definitely adversely disrupt the flow of bottles probably requiring the conveyor to be stopped. Systems of this type are called xe2x80x9cboppersxe2x80x9d or xe2x80x9cbang-bangxe2x80x9d systems because of their mode of action. In fact, the mode of action can result in cleanly rejected bottles being thrown over and cause significant problems downstream even if the bottles do manage to exit and remain outside of the path of the line of accepted bottles. U.S. Pat. No. 5,979,635 discloses a system of using a type of divertor assembly of the bopper-type as described above but with provision to extend the servoactivator in a controlled predetermined manner to a position adjacent to the article to be deflected where, preferably, it pauses prior to initiating the actual diversion of the article according to an ejection waveform. This is said to reduce the impact of the pad strike on the container and minimize the opportunity for the bottle to fall over. It does not, of course address other problems associated with this type of divertor. It also requires relatively complex and expensive equipment to detect the lateral position of the bottles on the conveyor. In an attempt to reduce any tendency to topple the bottles, the pad is usually constructed from a soft plastic material. This, however, introduces its own problems with respect to increased wear etc. loss of controlled contact with the bottle thus requiring relatively frequent maintenance.
In any event, all these fluid-based systems are subject to certain inherent or built-in delays in their operation in view of the several mechanical etc. steps in the system which steps need to be completed from the time the signal to reject is received by the device to the time the bottle contacting bopper is returned to its base position. In other words there are lags and overshoots inherent in such systems which are at best only minimized.
There are other types of divertors, for example, those which utilize a system which is generally able to effect transfer of a article from one conveyor to another over an extended length of travel and time, refer for example to U.S. Pat. No. 3,471,012. The smoothness and gentle transfer action involved should allow these divertors to be operated at high rates of transfer compared with the relatively more violent actions of the bopper-type devices. However some of these devices, refer for example to that described in U.S. Pat. No. 3,471,012 use selective activation of the article pusher members and this involves a substantial time factor. A similar type of device is described in U.S. Pat. No. 4,501,365 this device using a plurality of article pusher members controlled by an upstream apparatus for determining the relative position of articles on the conveyor. This device is extremely expensive and complex involving high maintenance and physically significant floor space.
The present invention provides a device and method for selectively removing an article from a stream or line of similar articles travelling in a pathway on a transport system such as a conveyor. The invention utilizes a synchronous electric motor which, in response to a signal to reject a specific article in the stream, rotates an article-contacting member or paddle into the path of the stream of articles travelling along the pathway whereby it contacts and smoothly removes that article from the stream. The use of a synchronous motor to effect the rotation of the paddle is very important to the present invention. Such a motor, characteristically,
(i) Has an extremely fast response time
(ii) Can readily and easily be programmed to rotate a desired amount and
(iii) Return to its original or base position extremely rapidly.
The manner in which the synchronous motor operates will be well known to one skilled in the art. However, briefly the motor has a built in program which effects a xe2x80x9ccountxe2x80x9d which represents one revolution of its drive shaft. For example, the count may be 8000. According to the present inventors, if the paddle is mounted directly on the drive shaft, this would mean that the paddle member would rotate 360xc2x0 for a full count of 8000. It is therefore, a relatively easy matter to program the motor to turn its drive shaft a set number of counts which equates to a desired part-rotation of the shaft which itself equates to a set degree of rotation of the paddle across the pathway. The count number entered into the motor and hence the amount of arc travelled by the paddle can depend on bottle type, conveyor track and track lubrication type. The speed and extent of the rotation of the paddle is important to the amount of thrust imparted to the article to be removed from the line and enable it to reach its required destination. In general, the articles quite frequently travel relatively close to the sidewall or rail of the conveyor and the articles in a stream maintain a similar distance from the sidewall. For example, in a modern brewery bottling line, the bottles will generally not be more than about 1.25 cm and usually only about 0.15 cm from the sidewall and the smooth paddle action of the present invention can handle such variances. However, to optimize performance, some adjustment of the speed or acceleration of the paddle may be required. The paddle is, generally, located in a slot formed by removing a short section of the sidewall and hence the distance the line of articles is laterally spaced from the paddle is about the same as from the sidewall. The paddle may be driven indirectly by the motor through mechanical linkages, gears, belts or the like. However, in a preferred embodiment, the paddle is mounted directly onto the drive shaft of the motor, this avoiding any lag or delay in rotation of the paddle because of mechanical linkages between the drive and the paddle. Initially the paddle is lying at a rest position generally adjacent and parallel to the path of the stream of articles. The paddle member which is initially parallel to the line of bottles, as it rotates is at a diminishing obtuse angle to the path of the stream of articles. The movement of the paddle is arranged to commence as the article to be rejected reaches the location of the paddle, generally the upstream part of the paddle.
Consequently, as the paddle swings into the path of the article to be rejected, the article will contact the moving paddle which will, at that point, be angled slightly into the travelling article path. It will be appreciated that this type of engagement between the bottle and the paddle means that the position of the article on the conveyor, laterally across the conveyor and longitudinally along the paddle length, is not as critical as it is in the case of the prior out devices since the article can slide along the paddle to some extent and for a relatively long period of time as it is swept out of the stream. Following that initial engagement the paddle continues its rotation until it has rotated through a predetermined angle or degree of arc which, in combination with the speed the paddle moves determines the force applied to the article and distance and direction the diverted article takes. In fact, the paddle accelerates and subsequently, decelerates to a stop, in the embodiments where it then reverses motion to regain its rest position. The action of the paddle may be likened to that of a sling as it sweeps the article out of the line of articles rather than a trust action used by the prior and bopper type devices. The shape or configuration of the paddle can vary depending on the articles, which are to be handled. Article characteristics such as height, length and width as well as weight distribution and centre of gravity can have an effect on the paddle configuration. Such factors will also need to be taken into account when choosing the required synchronous motor especially the weight of the article involved. For example, if the article is a rectangular box having a low height relative to its length, then the risk of it being tipped over when being contacted by the paddle is small and the height of the paddle is not critical. However, in the opposite situation, where an upright thin article is involved, for example a bottle, (the specific example chosen to describe the present invention) the vertical location along the article where the paddle exerts its diversion thrust becomes important. As indicated earlier, this is the case when the article is circular and especially when this has a high height-to-width ratio and may be in a relatively unstable equilibrium state. Of particular note is when the article is a bottle especially when filled. In this situation, care must be taken to minimize the possibility of the bottle being toppled by being contacted at a position too high or too low up the bottle by the paddle. In such cases, if contact is made too high up the bottle, rather than the upright bottle moving across the conveyor in an upright orientation, the bottle neck may rotate away from the paddle: when contact is made too low, then the bottle neck may rotate toward the paddle. In either case, the bottle may have a tendency to topple. In fact it has been found that the risk of an article, especially bottles and those having a similar weight/height profile, falling can be reduced by ensuring that the force exerted on the article by the sweeping motion of the paddle is applied, at least initially, through the article, in this case a bottle, at a position at about the bottle centre of gravity or a short distance there below. This reduces or prevents any tendency for the edge of the base of the bottle radially opposite the point of contact of the paddle with the bottle from being urged with any significant force against the conveyor surface thereby increasing resistance to the bottle commencing to slide laterally across the conveyor possibly causing it to tip over and fall. In summary, there is little or no tendency for the then edge of the bottle to xe2x80x9cdig-inxe2x80x9d and cause a problem.
However, in many operations and the bottle example referred to above is one, a lubricant is used to reduce the friction between the bottle base and the conveyor surface and assist the bottle slide. This appears to function adequately once the bottle starts to slide.
However, it is believed that the lubricant on the conveyor can itself cause a problem namely the base of a bottle may, as it travels along carried by the conveyor because of surface tension or other effects, have a tendency to adhere to the conveyor surface. In such a case, the action of the paddle can have the effect of moving the upper part of the bottle without, initially, the base sliding on the conveyor. The result again could be the bottle topples over. In a preferred embodiment of the invention the paddle plate is inclined slightlyxe2x80x94say 5-10xc2x0xe2x80x94from the vertical toward the bottle pathway. In this way, the upper edge of the paddle plate contacts the bottle fractionally before the remainder of the plate. This provides for a brief movementxe2x80x94small rotation in a vertical planexe2x80x94of the bottle, this breaking any xe2x80x9csealxe2x80x9d between the conveyor track and the base of a bottle. However, immediately following that action, the bottle body is contacted by the remainder i.e. lower portion of the paddle plate and any further rotational movement of the bottle is prevented, the bottle is rapidly righted, and commences sliding in an upright condition across the conveyor. It should be borne in mind that the action to right the bottle following the seal must be rapid since otherwise, the rapidly moving conveyor would pull the angled bottle, which would be unstable at that point, and tend to make it topple.
It will be appreciated that the orientation of the paddle in this preferred embodiment also takes into account tendencies of modern beverage bottles, especially beer bottles, to have a cylindrical body whose wall slopes slightly inward from the lower portion above the base to the shoulder area. In addition, the area immediately above the base extends radially further outwardly than the remainder of the main body area to provide a xe2x80x9cbumperxe2x80x9d zone. If adjacent bottles do contact each other it is via the bumper zone which prevents the upper cylindrical body areas from contacting. Since the body labels are usually carried by such areas, scuffing of the labels is also prevented or reduced.
The present invention has been described in detail with reference to the brewing industry and in particular, the handling of bottles, both full and filled with a beverage, at high speed. However it will be appreciated that it applies to any application where it is necessary to sort, divert or reject an unacceptable item from a line of such items travelling on a conveyor. It could, for example be used to reject or sort boxes; food items, many articles of manufacture, etc. all of which are able to be checked against standard characteristics and need to be sort or rejected based thereon. Obviously, items different from the specifically described bottles may require changes in the elements of the invention for example, a more powerful synchronous motor; change in paddle design etc. but these required adjustments can be determined and implemented by a man skilled in the art.